CN113075327B - Method for determining ethanol in air by utilizing sweeping and trapping - Google Patents
Method for determining ethanol in air by utilizing sweeping and trapping Download PDFInfo
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 title claims abstract description 126
- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000010408 sweeping Methods 0.000 title abstract description 6
- 238000010926 purge Methods 0.000 claims abstract description 32
- 238000004458 analytical method Methods 0.000 claims abstract description 3
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 45
- 239000004917 carbon fiber Substances 0.000 claims description 45
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 41
- 238000010521 absorption reaction Methods 0.000 claims description 32
- 239000007789 gas Substances 0.000 claims description 28
- 238000010438 heat treatment Methods 0.000 claims description 27
- 238000003756 stirring Methods 0.000 claims description 24
- 239000002131 composite material Substances 0.000 claims description 21
- 238000007789 sealing Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 239000011248 coating agent Substances 0.000 claims description 15
- 238000000576 coating method Methods 0.000 claims description 15
- 239000000835 fiber Substances 0.000 claims description 13
- 238000001819 mass spectrum Methods 0.000 claims description 13
- 238000003795 desorption Methods 0.000 claims description 12
- 150000002500 ions Chemical class 0.000 claims description 12
- 238000003763 carbonization Methods 0.000 claims description 9
- 239000000243 solution Substances 0.000 claims description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 8
- QMKYBPDZANOJGF-UHFFFAOYSA-N benzene-1,3,5-tricarboxylic acid Chemical compound OC(=O)C1=CC(C(O)=O)=CC(C(O)=O)=C1 QMKYBPDZANOJGF-UHFFFAOYSA-N 0.000 claims description 8
- 238000007664 blowing Methods 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 7
- 238000005406 washing Methods 0.000 claims description 7
- 230000005526 G1 to G0 transition Effects 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 6
- 238000005070 sampling Methods 0.000 claims description 5
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 4
- CDVAIHNNWWJFJW-UHFFFAOYSA-N 3,5-diethoxycarbonyl-1,4-dihydrocollidine Chemical compound CCOC(=O)C1=C(C)NC(C)=C(C(=O)OCC)C1C CDVAIHNNWWJFJW-UHFFFAOYSA-N 0.000 claims description 4
- 239000000853 adhesive Substances 0.000 claims description 4
- 230000001070 adhesive effect Effects 0.000 claims description 4
- 229910021529 ammonia Inorganic materials 0.000 claims description 4
- SXTLQDJHRPXDSB-UHFFFAOYSA-N copper;dinitrate;trihydrate Chemical compound O.O.O.[Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O SXTLQDJHRPXDSB-UHFFFAOYSA-N 0.000 claims description 4
- 239000012153 distilled water Substances 0.000 claims description 4
- 238000000642 dynamic headspace extraction Methods 0.000 claims description 4
- 238000010041 electrostatic spinning Methods 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 229920001568 phenolic resin Polymers 0.000 claims description 4
- 239000005011 phenolic resin Substances 0.000 claims description 4
- 229920002635 polyurethane Polymers 0.000 claims description 4
- 239000004814 polyurethane Substances 0.000 claims description 4
- 230000005540 biological transmission Effects 0.000 claims description 3
- 239000008367 deionised water Substances 0.000 claims description 3
- 229910021641 deionized water Inorganic materials 0.000 claims description 3
- 239000004205 dimethyl polysiloxane Substances 0.000 claims description 3
- 235000013870 dimethyl polysiloxane Nutrition 0.000 claims description 3
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 239000002904 solvent Substances 0.000 claims description 3
- 238000001514 detection method Methods 0.000 abstract description 18
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 abstract description 6
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 4
- 230000003068 static effect Effects 0.000 abstract description 4
- 230000035945 sensitivity Effects 0.000 abstract description 3
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 abstract description 2
- 239000000126 substance Substances 0.000 abstract description 2
- 239000000523 sample Substances 0.000 description 28
- 239000003570 air Substances 0.000 description 12
- 239000012621 metal-organic framework Substances 0.000 description 5
- 208000033962 Fontaine progeroid syndrome Diseases 0.000 description 2
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 2
- 239000002250 absorbent Substances 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910001431 copper ion Inorganic materials 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000010812 external standard method Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000012488 sample solution Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
- G01N1/2202—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling
- G01N1/2214—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling by sorption
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
- G01N1/2273—Atmospheric sampling
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
- G01N1/2202—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling
- G01N1/2214—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling by sorption
- G01N2001/2217—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling by sorption using a liquid
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Biomedical Technology (AREA)
- Molecular Biology (AREA)
- Engineering & Computer Science (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention discloses a method for determining ethanol in air by utilizing purging and trapping. The invention adopts the gas chromatograph to detect, can perform more accurate quantitative detection, eliminates the false positive condition by ion fragments, particularly the interference of substances such as methanol, glycol and the like, has lower detection limit and more sensitivity, and can reach the minimum detection limit of 0.02mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the Compared with a common static headspace, the pretreatment has the advantages that the sweeping and trapping technology is adopted, so that gas continuously passes through a sample, volatile components in the gas are extracted and then trapped, the gas is continuously extracted in an unbalanced state, and compared with the static headspace, the analysis sensitivity of the dynamic headspace is greatly improved; the method for determining the ethanol in the air by utilizing the sweeping and trapping solves the problem that the ethanol cannot be detected in the prior art, and has higher practicability.
Description
Technical Field
The invention relates to the technical field of environmental detection, in particular to a method for determining ethanol in air by utilizing sweeping and trapping.
Background
Ethanol, also called alcohol, is a saturated monohydric alcohol, is colorless, transparent, volatile and flammable, has very wide application in daily life, is widely used in industries such as industry, medical treatment, organic synthesis, food, printing and the like, inevitably causes that molecules are more or less filled in the air breathed by people, and has a certain influence on the body of people.
With the continuous development of modern industry and the progress of society, pollution of VOCs in air is increasingly concerned, and particularly precursor organic matters capable of forming ozone, ethanol is also gradually paid attention to as the ozone precursor organic matters. However, there is no standard method for detecting ethanol in the gas phase.
The invention provides a method for determining ethanol in air by utilizing purge and trap to solve the problems.
Disclosure of Invention
The invention aims to provide a method for determining ethanol in air by utilizing purging and trapping so as to solve the problems in the background art.
In order to solve the technical problems, the invention provides the following technical scheme:
a method for determining ethanol in air by utilizing purge and trap, comprising the following steps:
s1: collecting a sample, and sealing after completion;
s2: and (3) blowing the sample into a gas chromatograph-mass spectrometer after purging and trapping, analyzing the sample and calculating to obtain the concentration of the ethanol.
Further, the step S1:
taking an absorption bottle filled with distilled water, introducing gas to be detected at a certain flow rate, collecting for a period of time, and sealing the absorption bottle for later use;
further, the step S2:
and placing the absorption bottle on an automatic sampler of a purging and trapping instrument, heating, blowing nitrogen into the purging and trapping instrument, concentrating and trapping, and then, analyzing by a gas chromatograph-mass spectrometer after desorption, detecting a sample, and calculating the concentration of ethanol in the sample.
Further, the step S1:
placing an absorption bottle filled with distilled water in a detection environment, introducing gas to be detected at a flow rate of 100-150 ml/min, sampling for 200min, and sealing the absorption bottle for later use;
further, the step S2:
and placing the absorption bottle on an automatic sampler of a purging and trapping instrument, heating, blowing nitrogen into the purging and trapping instrument, concentrating and trapping, and then, analyzing by a gas chromatograph-mass spectrometer after desorption, detecting a sample, and calculating the concentration of ethanol in the sample.
Further, after the gas to be detected is collected, the cover with the pipe is taken down, the cover with the sealing gasket is covered, the sealing treatment is carried out, and the cover with the sealing gasket can be connected with the purging trapping instrument.
Further, the inner wall of the absorption bottle is coated with a carbon fiber coating.
Further, the preparation method of the carbon fiber coating comprises the following steps:
placing phenolic resin in ethanol, uniformly stirring, adding ferric acetylacetonate, uniformly stirring, carrying out ultrasonic oscillation, stirring for a period of time, preparing composite fibers from the mixed liquid by using an electrostatic spinning method, carbonizing the composite fibers for a period of time, heating the composite fibers for a period of time in an ammonia environment, placing the composite fibers in a mixed solution of sulfuric acid and hydrogen peroxide, stirring for a period of time, and washing to obtain carbon fibers;
placing the carbon fiber in a copper nitrate trihydrate solution, heating in a water bath, carrying out ultrasonic vibration, uniformly stirring, adding trimesic acid, heating in a water bath, carrying out ultrasonic vibration, and uniformly stirring to obtain a carbon fiber composite material;
and (3) bonding the carbon fiber composite material on the inner wall of the absorption bottle by using a polyurethane adhesive to prepare the carbon fiber coating.
Further, the preparation method of the carbon fiber coating comprises the following steps:
placing phenolic resin in ethanol, mechanically stirring for 20-30 min, adding ferric acetylacetonate, mechanically stirring for 20-30 min, ultrasonically oscillating for 5-10 min, mechanically stirring for 6-8 h, preparing composite fibers from the mixed liquid by using an electrostatic spinning method, heating the composite fibers to 150 ℃ for carbonization for 2h, heating to 170 ℃ for carbonization for 1h, heating to 190 ℃ for carbonization for 1h, placing in an ammonia environment, heating the composite fibers to 700 ℃ for 1h, heating to 950 ℃ for 1h, placing in a sulfuric acid and hydrogen peroxide mixed solution, mechanically stirring for 3-4 h, washing for 3-4 times by using hydrochloric acid, and washing for 3-4 times by using deionized water to obtain carbon fibers;
placing the carbon fiber in a copper nitrate trihydrate solution, heating the carbon fiber in a water bath to 50 ℃, carrying out ultrasonic vibration for 5-10 min, mechanically stirring for 10-20 min, adding trimesic acid, heating the carbon fiber in the water bath to 65 ℃, carrying out ultrasonic vibration for 10-15 min, and mechanically stirring for 10-20 min to obtain a carbon fiber composite material;
and (3) bonding the carbon fiber composite material on the inner wall of the absorption bottle by using a polyurethane adhesive to prepare the carbon fiber coating.
Further, the absorption bottle is a brown bubble absorption bottle.
Further, the conditions of the purging and trapping device are as follows:
the temperature of the valve oven is 140 ℃;
the temperature of the transmission line is 140 ℃;
the temperature of the sample rack is 90 ℃;
the sample purging time is 10min;
the purging flow rate is 40ml/min;
the dry purge time was 1min;
the pre-desorption temperature is 160 ℃;
the desorption temperature is 180 ℃;
the desorption time was 2min.
Further, the gas chromatography conditions of the gas chromatograph-mass spectrometer are as follows:
the chromatographic column is Rtx-624,60m multiplied by 0.25mm;
6% by weight of the chromatographic column stationary phase coating raw material is nitrile propyl phenyl and 94% by weight of the chromatographic column stationary phase coating raw material is dimethyl polysiloxane fixing solution;
the thickness of the chromatographic column is 1.4 mu m;
the chromatographic column temperature-rising program is as follows: the initial temperature is 35 ℃, the temperature is raised to 100 ℃ at the speed of 20 ℃/min after the temperature is kept for 1min, and the temperature is kept for 0.75min;
the mass spectrum conditions are as follows:
the temperature of the ion source is 200 ℃;
the interface temperature is 200 ℃;
the scanning mode is scan;
the scanning range is 30-50 amu;
the solvent delay was 2.2min.
Further, another absorption bottle with the same condition is placed in the detection environment, the gas to be detected is not introduced, and the rest treatment is the same as the sample and is marked as a blank control.
Further, ethanol solutions with different concentrations are used for drawing an ethanol standard curve chart by a gas chromatograph-mass spectrometer, the ethanol concentration is taken as an abscissa, and the peak area is taken as an ordinate.
Further, the mass spectrum quantitative ion peak area of the sample is subtracted from the mass spectrum quantitative ion peak area of the blank control, and the ethanol concentration in the sample is calculated by using a curve equation in an ethanol standard curve chart.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a method for determining ethanol in air by utilizing purging and trapping. The carbon fiber is prepared in the implementation process, the prepared carbon fiber has a large number of medium-sized holes, the carbon fiber in the prior art has a large number of micropores, a large number of ethanol molecules can be adsorbed, but the micropores can cause large diffusion resistance of the ethanol molecules in the carbon fiber to influence the adsorption efficiency of the carbon fiber, the prepared carbon fiber has a large number of micropores and medium-sized holes, the carbon fiber has extremely high specific surface area, can adsorb a large number of ethanol molecules, can also combine the micropores with the medium-sized holes to use, improves the diffusion rate of the ethanol molecules, and meanwhile, the inner wall of an absorption bottle is coated with the carbon fiber to ensure complete absorption of the ethanol molecules in the air;
meanwhile, the metal organic framework is synthesized on the surface of the carbon fiber in situ, because the surface of the carbon fiber is provided with a large number of oxygen-containing groups, copper ions can coordinate with carboxyl groups on the surface of the carbon fiber, meanwhile, the metal organic framework is generated on the surface of the carbon fiber, and grows on the surface of the carbon fiber in situ, so that the stability and strength of the metal organic framework are improved, meanwhile, the metal organic framework is provided with an extremely high specific surface area and a large number of holes, and a large number of ethanol molecules are adsorbed through the electrostatic action of the metal organic framework;
meanwhile, the invention adopts the gas chromatograph to detect, so that more accurate quantitative detection can be performed, false positive conditions, especially interference of substances such as methanol, glycol and the like, are eliminated through ion fragments, the detection limit is lower, the detection is more sensitive, and the minimum detection limit can reach 0.02mg/m 3 ；
Compared with a common static headspace, the purging and trapping technology has the advantages that the purging and trapping technology enables gas to continuously pass through a sample, volatile components in the gas are extracted and then trapped, and the purging and trapping technology is non-equilibrium continuous extraction, so that the analysis sensitivity of the dynamic headspace is greatly improved compared with the static headspace;
meanwhile, the invention improves the absorption bottle, after the collection of the gas to be detected is completed, the cover with the pipe (shown in figure 8) is taken down, the cover with the sealing gasket (shown in figure 9) is covered for sealing treatment, the cover with the sealing gasket can be connected with the purging trapping instrument, the volatilization of ethanol caused by transferring the absorption liquid in the absorption bottle into the purging bottle is avoided, finally experimental data is inaccurate, experimental errors are further reduced by improving the absorption bottle, and experimental precision is improved;
the method for determining the ethanol in the air by utilizing the sweeping and trapping solves the problem that the ethanol cannot be detected in the prior art, and has higher practicability.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention. In the drawings:
FIG. 1 is a standard graph of ethanol;
FIG. 2 is a quantitative mass spectrum of ethanol concentration of 0.2 mg/L;
FIG. 3 is a quantitative mass spectrum of ethanol concentration of 0.5 mg/L;
FIG. 4 is a quantitative mass spectrum of ethanol at 1.0 mg/L;
FIG. 5 is a quantitative mass spectrum of ethanol at a concentration of 2.0 mg/L;
FIG. 6 is a quantitative mass spectrum of ethanol at 5.0 mg/L;
FIG. 7 is a quantitative mass spectrum of ethanol at a concentration of 10.0 mg/L;
FIG. 8 is a schematic view of an absorbent bottle capped with a tube cap;
fig. 9 is a schematic view of an absorbent bottle capped with a cap with a sealing gasket.
Detailed Description
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
A method for determining ethanol in air by utilizing purge and trap, comprising the following steps:
s1: collecting a sample, and sealing after completion;
s2: and (3) blowing the sample into a gas chromatograph-mass spectrometer after purging and trapping, analyzing the sample and calculating to obtain the concentration of the ethanol.
Wherein S1:
(1) Placing phenolic resin in ethanol, mechanically stirring for 20-30 min, adding ferric acetylacetonate, mechanically stirring for 20-30 min, ultrasonically oscillating for 5-10 min, mechanically stirring for 6-8 h, preparing composite fibers from the mixed liquid by using an electrostatic spinning method, heating the composite fibers to 150 ℃ for carbonization for 2h, heating to 170 ℃ for carbonization for 1h, heating to 190 ℃ for carbonization for 1h, placing in an ammonia environment, heating the composite fibers to 700 ℃ for 1h, heating to 950 ℃ for 1h, placing in a sulfuric acid and hydrogen peroxide mixed solution, mechanically stirring for 3-4 h, washing for 3-4 times by using hydrochloric acid, and washing for 3-4 times by using deionized water to obtain carbon fibers;
(2) Placing the carbon fiber in a copper nitrate trihydrate solution, heating the carbon fiber in a water bath to 50 ℃, carrying out ultrasonic vibration for 5-10 min, mechanically stirring for 10-20 min, adding trimesic acid, heating the carbon fiber in the water bath to 65 ℃, carrying out ultrasonic vibration for 10-15 min, and mechanically stirring for 10-20 min to obtain a carbon fiber composite material;
(3) The carbon fiber composite material is adhered to the inner wall of an absorption bottle by using a polyurethane adhesive to prepare a carbon fiber coating;
(4) Placing an absorption bottle filled with distilled water in a detection environment, introducing gas to be detected at a flow rate of 100ml/min, sampling for 200min, and sealing the absorption bottle for later use;
(5) Placing the absorption bottle with the same condition in a detection environment, not introducing the gas to be detected, and marking the rest treatment as blank control, wherein the rest treatment is the same as that of the sample;
wherein S2:
(1) Respectively transferring 10, 25, 50, 100, 250 and 500 mu L of ethanol standard intermediate solution (250 mg/L) into a 20ml volumetric flask filled with blank water, configuring standard series with target concentrations of 0.2, 0.5, 1.0, 2.0, 5.0 and 10.0mg/L, sequentially injecting samples from low concentration to high concentration according to the condition of a Shimadzu gas chromatograph-mass spectrometer GCMS-QP2020NX, and recording the retention time and quantitative ion response of ethanol;
quantitative ion for ethanol 31, auxiliary ion 45, and measurement using full scan, data are shown in the following table;
the retention time of the target compound ethanol is determined to be 2.9min through qualitative analysis, the mass spectrum quantitative ion peak area (the following table) of each concentration of ethanol is obtained according to the quantitative mass spectrogram (fig. 2 to 7) of each concentration of ethanol, the external standard method is used for calculating, the sample concentration is used as an abscissa, the peak area is used as an ordinate, a standard curve chart (fig. 1) of the ethanol is drawn, and the curve equation is y=214982.537695 x+22223.757412;
(2) Placing an absorption bottle on an automatic sample injector of a purging and trapping instrument, setting the temperature of a valve oven and the temperature of a transmission line to 140 ℃, setting the temperature of a sample rack to 90 ℃, setting the purging time of a sample to 10min, setting the purging flow of the sample to 40ml/min, setting the purging time of a dry sample to 1min, setting the pre-desorption temperature to 160 ℃, setting the desorption temperature to 180 ℃, setting the desorption time to 2min, blowing nitrogen into the purging and trapping instrument, trapping and concentrating, and blowing a gas chromatograph-mass spectrometer for detection after reheating;
(3) The detecting instrument is a Shimadzu gas chromatograph-mass spectrometer GCMS-QP2020NX, the chromatographic column is Rtx-624,60m is multiplied by 0.25mm, the film thickness is 1.4 mu m (nitrile propyl phenyl accounting for 6 percent of the weight of the stationary phase coating raw material and dimethyl polysiloxane fixing liquid accounting for 94 percent of the weight of the stationary phase coating raw material), and the chromatographic column temperature-rising program is as follows: the initial temperature is 35 ℃, the temperature is raised to 100 ℃ at the speed of 20 ℃/min after the initial temperature is kept for 1min, the temperature of an ion source and an interface is set to 200 ℃, the scanning mode is scan, and the scanning range is as follows: 30-50 amu, and the solvent delay is 2.2min;
(4) Carrying out 8 times of detection on the same sample, subtracting the mass spectrum quantitative ion peak area of a blank control from the mass spectrum quantitative ion peak area of the sample, calculating the ethanol concentration in the sample by using a curve equation in an ethanol standard curve chart, and calculating the ethanol concentration in the gas to be detected by using a formula;
concentration of ethanol byCalculating;
wherein the concentration of ethanol in the c-ambient air and exhaust gas (mg/m 3 )；
Concentration of ethanol in the W-sample absorption liquid (mg/L);
V 1 -sample solution volume (ml);
V n -a sampling volume (L) of the standard state sample.
Experimental data
| Sequence number | Concentration value (mg/m) 3 ) |
| 1 | 0.145 |
| 2 | 0.156 |
| 3 | 0.163 |
| 4 | 0.157 |
| 5 | 0.154 |
| 6 | 0.155 |
| 7 | 0.169 |
| 8 | 0.158 |
| Standard deviation of | 0.007 |
| Detection limit | 0.02 |
Data analysis
The detection limit of the invention is as low as 0.02mg/m 3 According to the embodiment results, the carbon fiber coating prepared by the invention has good adsorption effect, extremely small detected data deviation and high accurate detection result, improves the detection precision of the concentration of ethanol in the ambient air and the waste gas through a dynamic headspace and gas mass spectrometer, solves the problem that the concentration of ethanol in the air cannot be detected in the prior art, and has higher practicability.
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. A method for determining ethanol in air by utilizing purge and trap, which is characterized by comprising the following steps: the method comprises the following steps:
s1: taking an absorption bottle filled with distilled water, introducing gas to be detected at a certain flow rate, collecting for a period of time, and sealing the absorption bottle for later use;
s2: placing an absorption bottle on an automatic sampler of a purging and trapping instrument, heating, blowing nitrogen into the purging and trapping instrument for concentration and trapping, and then, entering a gas chromatograph-mass spectrometer for analysis after desorption, detecting a sample, and calculating the concentration of ethanol in the sample; wherein the inner wall of the absorption bottle is coated with a carbon fiber coating;
the preparation method of the carbon fiber layer comprises the following steps:
(1) Placing phenolic resin in ethanol, mechanically stirring for 20-30 min, adding ferric acetylacetonate, mechanically stirring for 20-30 min, ultrasonically oscillating for 5-10 min, mechanically stirring for 6-8 h, preparing composite fibers from the mixed liquid by using an electrostatic spinning method, heating the composite fibers to 150 ℃ for carbonization for 2h, heating to 170 ℃ for carbonization for 1h, heating to 190 ℃ for carbonization for 1h, placing in an ammonia environment, heating the composite fibers to 700 ℃ for 1h, heating to 950 ℃ for 1h, placing in a sulfuric acid and hydrogen peroxide mixed solution, mechanically stirring for 3-4 h, washing for 3-4 times by using hydrochloric acid, and washing for 3-4 times by using deionized water to obtain carbon fibers;
(2) Placing the carbon fiber in a copper nitrate trihydrate solution, heating the carbon fiber in a water bath to 50 ℃, carrying out ultrasonic vibration for 5-10 min, mechanically stirring for 10-20 min, adding trimesic acid, heating the carbon fiber in the water bath to 65 ℃, carrying out ultrasonic vibration for 10-15 min, and mechanically stirring for 10-20 min to obtain a carbon fiber composite material;
(3) The carbon fiber composite material is adhered to the inner wall of an absorption bottle by using a polyurethane adhesive to prepare a carbon fiber coating;
s1, introducing air with the flow rate of 100-150 ml/min and the sampling time of 200min;
the absorption bottle is a brown bubble absorption bottle;
after the gas to be detected is collected in the absorption bottle, the cover with the pipe is taken down, the cover with the sealing gasket is covered, the sealing treatment is carried out, and the cover with the sealing gasket is connected with the purging trapping instrument;
in S2, the gas chromatograph conditions of the gas chromatograph-mass spectrometer are:
the chromatographic column is Rtx-624,60m multiplied by 0.25mm;
6% by weight of the chromatographic column stationary phase coating raw material is nitrile propyl phenyl and 94% by weight of the chromatographic column stationary phase coating raw material is dimethyl polysiloxane fixing solution;
the thickness of the chromatographic column is 1.4 mu m;
the chromatographic column temperature-rising program is as follows: the initial temperature is 35 ℃, the temperature is raised to 100 ℃ at the speed of 20 ℃/min after the temperature is kept for 1min, and the temperature is kept for 0.75min;
the mass spectrum conditions are as follows:
the temperature of the ion source is 200 ℃;
the interface temperature is 200 ℃;
the scanning mode is scan;
the scanning range is 30-50 amu;
the solvent delay was 2.2min.
2. A method for determining ethanol in air using purge capture as claimed in claim 1, wherein: in S1, the flow rate of the air is 100-150 ml/min, and the sampling time is 200min.
3. A method for determining ethanol in air using purge capture as claimed in claim 1, wherein: in S2, the conditions of the purge-trap instrument are:
the temperature of the valve oven is 140 ℃;
the temperature of the transmission line is 140 ℃;
the temperature of the sample rack is 90 ℃;
the sample purging time is 10min;
the sample purging flow rate is 40ml/min;
the dry purge time was 1min;
the pre-desorption temperature is 160 ℃;
the desorption temperature is 180 ℃;
the desorption time was 2min.
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| WO2021003316A1 (en) * | 2019-07-01 | 2021-01-07 | Perkinelmer Health Sciences, Inc. | Pdms granular coated vial |
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| WO2021003316A1 (en) * | 2019-07-01 | 2021-01-07 | Perkinelmer Health Sciences, Inc. | Pdms granular coated vial |
Non-Patent Citations (5)
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| Zhi-Guo Qu et al..Highly efficient adsorbent design using a Cu-BTC/CuO/carbon fiber paper composite for high CH4/N2 selectivity.《RSC Adv.》.2017,第7卷摘要，第14207页. * |
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